1. Field of the Invention
The present invention relates to an ultrasound vibration device which excites ultrasound vibration, a method of manufacturing the ultrasound vibration device, and an ultrasound medical apparatus provided with the ultrasound vibration device.
2. Description of the Related Art
Recently, ultrasound medical apparatuses include, for example, an ultrasound treatment instrument for performing coagulation/dissection treatment of living tissue. The ultrasound treatment instrument is provided with an ultrasound transducer which generates ultrasound vibration.
Some of conventional ultrasound treatment instruments internally include a bolted Langevin transducer, for example, as shown in Japanese Patent Application Laid-Open Publication No. 2009-220014, in a handpiece as an ultrasound transducer (vibration source). In such a conventional bolted Langevin transducer, a piezoelectric element which converts an electric signal to mechanical vibration is firmly fastened with a bolt and integrated with a front mass and a back mass which are constituted by metallic members, being sandwiched between the front mass and the back mass, and a whole vibrates as an integrated body.
Note that such a transducer that a piezoelectric element is sandwiched between metallic members and vibrates being integrated with the metallic members by some method including adhesion and the like is referred to as a Langevin transducer, and a Langevin transducer adopting fastening with a bolt as an integration method is referred to as a bolted Langevin transducer. As a general configuration, lead zirconate titanate (PZT: Pb(Zrx,Ti1-x)03) is used for the piezoelectric element; the piezoelectric element is formed in a ring shape; and a bolt is inserted through an inside of the ring.
Because being highly productive and having a high electromechanical conversion efficiency and excellent characteristics as piezoelectric material, PZT as such a piezoelectric element has been used for various fields, such as an ultrasound transducer and actuator fields, for a long time.